1. Field
The following description relates to an apparatus and method for generating an acoustic radiation pattern, and more particularly, to an apparatus and method for allowing a speaker array system comprising a plurality of speakers to output a desired acoustic radiation pattern.
2. Description of the Related Art
A speaker array, which is a combination of a plurality of speakers, is used to control the direction of sound to be reproduced by combining a plurality of speakers or to transfer sound to a predetermined location. While a large speaker is naturally more directional because of its large size, a source with equivalent directivity can be made by utilizing an array of traditional small speakers, all driven together in phase. Acoustically equal to a large speaker, this creates a larger source size compared to wavelength, and the resulting sound field may be narrowed compared to a single small speaker. Large speaker arrays have been used in hundreds of arena sound systems to mitigate noise that would ordinarily travel to adjoining neighborhoods, as well as limited applications in other areas in which some degree of directivity is helpful, such as museums or similar display applications that can tolerate large speaker dimensions.
The principle of sound transmission, generally called “directivity,” is to make a plurality of sound source signals overlap each other using phase differences between the sound source signals in order to increase signal strength in a particular direction. As such, the sound source signals are transmitted in the particular direction. Thus, such directivity is realized by disposing a plurality of speakers in particular positions, and adjusting the source sound signals of the array, which are output through the speakers of the array.
A general array system calculates, in order to obtain a desired frequency beam pattern, filter values, i.e., gain and delay values suitable for the desired beam pattern. Thus, this method permits use of only one fixed beam pattern.
Recently, interest in a personal sound zone for transferring sound only to specific listeners without utilizing earphones or headsets, while not creating noise pollution to adjacent persons is increasing. A personal sound zone may be formed by driving a plurality of acoustic transducers to thereby acquire the directivity of sound. In order to utilize the directivity of sound, input signals which are to be output by a plurality of speakers need to be passed through functional filters such as time delay filters to concentrate sound in a particular direction or on a particular position, thereby creating sound beams.